91728218925225 has 135 divisors (see below), whose sum is σ = 170692713605799. Its totient is φ = 48698063330400.

The previous prime is 91728218925181. The next prime is 91728218925227. The reversal of 91728218925225 is 52252981282719.

The square root of 91728218925225 is 9577485.

It is a perfect power (a square), and thus also a powerful number.

91728218925225 is a `hidden beast` number, since 9 + 1 + 7 + 2 + 8 + 2 + 18 + 92 + 522 + 5 = 666.

It can be written as a sum of positive squares in only one way, i.e., 33022158813081 + 58706060112144 = 5746491^2 + 7661988^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is not a de Polignac number, because 91728218925225 - 2⁴¹ = 89529195669673 is a prime.

It is a super-2 number, since 2×91728218925225² (a number of 29 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (91728218925227) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 142656638754 + ... + 142656639396.

Almost surely, 2^{91728218925225} is an apocalyptic number.

91728218925225 is the 9577485-th square number.

91728218925225 is the 4788743-rd centered octagonal number.

It is an amenable number.

91728218925225 is a deficient number, since it is larger than the sum of its proper divisors (78964494680574).

91728218925225 is an frugal number, since it uses more digits than its factorization.

91728218925225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1970 (or 982 counting only the distinct ones).

The product of its digits is 29030400, while the sum is 63.

The spelling of 91728218925225 in words is "ninety-one trillion, seven hundred twenty-eight billion, two hundred eighteen million, nine hundred twenty-five thousand, two hundred twenty-five".